The flip chip mounting is a technique widely used in semiconductor devices.
In the flip chip mounting, a semiconductor element is mounted on a principal surface of a wiring board on which a wiring pattern is formed so that a surface of the semiconductor element on which an electrode pad is formed faces the principal surface of the wiring board, and the electrode pad is connected to the wiring pattern by solder bumps.
With the flip chip mounting, the wiring length between the semiconductor element and the wiring board may be shortened, and influences of a parasitic impedance or a parasitic inductance may be lessened. Heat generated by the semiconductor element may be effectively dissipated and transferred to the wiring board via solder bumps.
With the flip chip mounting, after the semiconductor element is mounted on the wiring board, an underfill resin is injected into a gap between the semiconductor element and the wiring board in order to protect the solder bump and the wiring pattern and to mechanically support the semiconductor element. The underfill resin is ordinarily supplied using a capillary action. Therefore, a resin which is excellent in wettability and flowability may be used as the underfill resin to prevent voids from being formed or the resin from being insufficiently supplied as described in Japanese Laid-open Patent Publication No. 2006-140327.